1. Field of the Invention
The present invention relates to a method for manufacturing a dielectric isolation type semiconductor device that can improve withstand voltage, and can prevent a semiconductor substrate from warping.
2. Background Art
In recent years, a dielectric isolation type semiconductor device wherein a semiconductor layer is bonded on a semiconductor substrate via a dielectric layer, and a power device is formed on the semiconductor layer has been proposed. However, in a conventional dielectric isolation type semiconductor device, the withstand voltage of the semiconductor device was limited depending on the thickness of the dielectric layer and the thickness of the semiconductor layer. In order to solve this problem, the formation of a thick dielectric layer locally on the major surface of a semiconductor substrate so as to contact the dielectric layer has been proposed (for example, refer to Japanese Patent Application Laid-Open No. 2005-175296).